Joysticks are conventionally utilized to provide positioning information in a two dimensional system. For example, joysticks are commonly used to position objects on the screen of a video game or to manipulate a machining tool about a two-dimensional work surface.
The typical joystick, such as that shown in U.S. Pat. No. 4,375,631, issued on Mar. 1, 1983 to Thomas R. Goldberg, consists of two potentiometers coupled to a control handle. As the handle is pivoted about two orthogonal axes, the resistance of the potentiometers varies in relation to the position of the handle. The value of the resistance or the magnitude of the current passing through the potentiometer indicates the position of the joystick handle about the corresponding axis. This resistance, or current, representing the handle's position is then utilized to control some other function such as the position of the video game object or the machine tool head. The movement of the handle may be used to dynamically control the object by continuously monitoring the change in the potentiometer resistance and employing the monitored resistance to move the object in a pattern corresponding to the movement of the joystick handle.
In some applications the object to be controlled by the joystick may need to be positioned or moved in a three dimensional space or twisted about any of three orthogonal axes. In such a case, the conventional joystick which is limited to controlling movement in only two dimensions is inadequate.